how would your 5/6 year olds work out 75-9?

[EweHaveGoatToBeKiddin]

Dd usually calculates with her fingers, but her sums have started getting trickier this week.

I'm not sure how to help her with this? At school she says they use a number grid to 100. I printed a similar one off lastnight but dd couldn't use it. She got confused when jumping to the row of numbers below as to what side she was on. Apart from a number grid is there any other way to help her learn these types of sums?

Cant get in to speak to the teacher until next week.

number line - you can use a tape measure. Then count 9 hops from 75 up to the answer.

its a takeaway sum Mary

Numberlines are great, if they use them often enough they can start to visualise them in their head.

With near 10's you can also encourage them to subtract 10 then add or take away 1 but that is more useful for a little older.

If the numbers are closer 84-80 for instance some will find it easier to count up instead but I wouldnt encourage that yet until she has a good sense of what subtract really really means. (you can start talking about the difference)

6yo dd says 'she uses the lines in her head'.

Not very helpful but both mine would say they couldn't do it as the number is too big (sigh!) - will read the answers and try and help them

ds would probably take 10 away and then add 1 back on so:

75-9 would be:
75 -10 = 65
65 + 1 = 66

75-10+1?

Not at age 5-6 perhaps but at age 6-7.

My nearly 6yo would utterly fail. He could probably count down okay on a 100 square, with some encouragement but he woudln't understand how it worked.

whoops, I did it as an addition too!

I help out in a year 1 class, and only about 5 or 6 of them could do this unaided, although another 10 could probably do it together with a number line.
Last week they were doing subtraction from 20 and top 2 groups could do it, but next group down needed reminding as they did it, and several kept getting the hops wrong, they found it hard to be precise and hop on the numbers

75

70-9

61

+5

66

A number grid for subtraction? Sounds like a terrible idea. I'd use a number line and when they were confident counting back 9 I'd show them that that is the same as counting back 10 and going forward 1. You can then move away from the line to digits because they should already be confident subtracting 10 and adding 1 using digits.

But I don't teach 5/6 year olds.

Thanks so much everyone.

I agree with the number grid being terrible. She just doesn't understand it all. As far as i can see, it only helps her to count in 10s.

I've printed off a number line to try with her later. Hopefully this will be easier to use than the grid was, since all the numbers are on one line.

I think the subtracting 10 then adding one might be too complex for her just now, but i'll definitely give it a try.

Ds would do the take away 10 then add on 1.

Have they been taught to look for patterns, ie subtracting 9 the first number goes down by 1 and the second goes up by 1? The 'why' could come later.

I don't know, am not a teacher or a parent of a 5/6 yo, just guessing really.

As I thought - neither the 5 or 6 year old DS would even have a go! Too hard and big a number apparently! Definitely something to work on! Sadly I think they may have my maths brain

75-9... 75-10 and 1. Write down different numbers and practice add and take away 10, 20. 30 just for her to get the idea of changing tens, leaving the units. Also try to use different verbs (9 less than 75 is).

My daughter had same targets in year 1 (2 digit number add/take away 1 digit number).

Print out a number grid and tell her that you will design a nice, colorful carpet. You call out a number (35), color it than he has to color 9 less. Take turns. Discuss the patterns. Later she will be able to find 9 less without counting back (jump 1 line up (-10) and jump 1 right (+1).

Hi, I would teach more able year 1 children to draw a number line.
So draw a straight line.
Write 75 at the far end.
Then draw 9 arcs backwards along the line (we called it jumps and had various animals jumping)
Write each number below the line where the arc touches (or animal lands) so 74, 73 usw.
The number written on the 9th (66) jump as it's your answer.

Sounds really complicated written like that but it's very simple. It's just counting backwards along a line really. The jumps just keep track.

Hope your DD gets it

www.abc123kidz.com/addition_strategies.html

Can't do active links sorry. There is an addition example about half way down. To subtract you just go the other way

DS1 (6 years, year 1) would do one of 2 approaches. He might use 75-10 is 65 therefore 75-9 is 66. Alternatively he might say 75-5= 70 and then take away another 4. Either way he seems to make use of his knowledge of number bonds to 10. He would be able to use these methods to do it mentally.